Join the items in {list} together into one String. When {sep} is specified it is put in between the items. If {sep} is omitted a single space is used. Note that {sep} is not added at the end. You might want to add it there too:

let lines = join(mylist, "\n") .. "\n"

String items are used as-is. Lists and Dictionaries are converted into a string like with string(). The opposite function is split().

Can also be used as a method:

mylist->join()